Blood purification systems, which are used for conducting hemodialysis, hemodiafiltration or hemofiltration, involve the extracorporeal circulation of blood through an exchanger having a semi permeable membrane. Such systems further include a hydraulic system for circulating blood and a hydraulic system for circulating replacement fluid or dialysate comprising the certain blood electrolytes in concentrations close to those of the blood of a healthy subject. Standard dialysis treatment comprises two phases, namely, (a) dialysis, in which toxic substances and scoriae (normally small molecules) pass through the semi-permeable membrane from the blood to the dialysis liquid, and (b) ultrafiltration, in which a pressure difference between the blood circuit and the dialysate circuit, more precisely a reduced pressure in the latter circuit, causes the blood content of water to be reduced by a predetermined amount.
During dialysis treatment, the dialysate is stored locally for infusion into the treatment process as needed. A standard cylindrical container is filled with various compositions and non-sterile or sterile water to produce the electrolyte or infusate. A tube is placed within the mixture for drawing the electrolyte into the filtering components of the dialysis machine. In order to properly perform the dialysis procedure, the amount and composition of the electrolyte must be continuously and accurately monitored.
One method of monitoring involves using an optical camera and a weight scale to monitor the composition and amount, respectively, of the electrolyte. For example, U.S. patent application Ser. No. 13/023,490, entitled “Portable Dialysis Machine”, filed on Feb. 8, 2011 and assigned to the applicant of the present invention, describes how “desired quantities of an infusate solution can be added to the dialysis fluid. Infusate is a solution containing minerals and/or glucose that help replenish minerals like potassium and calcium in the dialysate fluid at levels after undesired removal by the sorbent. A peristaltic pump is provided to pump the desired amount of infusate solution to [a] container. A camera may optionally be provided to monitor the changing liquid level of the infusate solution as a safety check warning of infusate flow failure . . . . The container is also equipped with a scale for keeping track of the weight, and therefore volume, of the fluid in the container.” U.S. patent application Ser. No. 13/023,490 is incorporated herein by reference in its entirety.
Although the use of a camera and scale provides a mechanism for monitoring the level and composition of electrolyte, an improved, non-invasive system to monitor electrolytes, while requiring fewer components and being more inexpensive and easier to commercially implement, is still needed.